The two major objectives of this project are: (1) to determine how binding of acetylcholine to its receptor molecule (R) causes a change in cation permeability of the post synaptic membrane, and (2) to determine whether the muscular paralysis induced in animals by immunization with R protein is a relevant model of myasthenia gravis (M.G.). R purified from Electrophorus electricus is being characterized biochemically and immunologically. Techniques for reconstituting acetylcholine sensitive cation permeability to membranes are being developed to allow functional characterization of the R macromolecule. Animals immunized with R are being examined as a model disease for M.G., and sera of human M.G. victims are being analyzed for antibody directed against R.